1. Field of the Invention
The present invention relates generally to devices for transporting light. More specifically, the invention relates to fiber bundles and methods for making fiber bundles.
2. Technical Background
In the fields of optical communication, laser machining, and optical sensing, it is often desirable to combine optical power from several sources into a single beam. For example, in sensing applications, a fiber bundle can be used to combine optical power of different wavelengths from different laser or lamp sources into a single beam. In certain high-power applications, a fiber bundle can combine optical power from several identical sources into a single beam of relatively high power. Fiber bundles may also be used to divide light from a single source into a plurality of beams, or to reshape a beam in order to couple it between different optical devices.
A conventional fiber bundle is shown in FIG. 1. Fiber bundle 20 has a terminal section 22, and an endface 24. Fiber bundle 20 includes a plurality of optical fibers 26, each of which has a terminal segment 28 ending with a proximal end 30, and a distal end 32. The terminal segments 28 of optical fibers 26 are arranged substantially in parallel, and are affixed to one another (e.g., with adhesive or by fusion) to form the terminal section 22 of fiber bundle 20. The proximal ends 30 of optical fibers 26 are presented at the endface 24 of fiber bundle 20. In order to reduce the size of the beam, it may be desirable to taper the terminal section of the fiber bundle, as shown in FIG. 1.
However, conventional fiber bundles have certain disadvantages. For example, especially in tapered fiber bundles, the terminal section of the fiber bundle is often very small and very fragile, making it difficult to handle and prone to breakage. Further, the outermost fibers of a conventional fiber bundle can separate from the interior fibers, causing both a physical fraying of the fiber bundle, and a corresponding fraying of the optical beam. Since it is difficult to remove airspace between fibers at the endface of the fiber bundle, polishing and AR coating of the endface can be complicated by the presence of particulate matter in any airspace. It is also difficult to precisely position with respect to one another the optical fibers of a conventional fiber bundle.